Muellbacher W, Artner C, Mamoli B
Ludwig Boltzmann Institute for Epilepsy and Neuromuscular Disorders, Second Department of Neurology, Neurological Hospital of Vienna, Austria.
J Neurol. 1999 Apr;246(4):250-6. doi: 10.1007/s004150050343.
Transcranial magnetic stimulation (TMS) of the motor cortex was used to study basic mechanisms of motor reorganization after major hemispheric stroke in humans. We sought to clarify the possible role of the intact hemisphere in motor recovery of the lingual muscles, and to evaluate the compensatory use of preexisting uncrossed motor pathways projecting to these midline muscles. TMS and bilateral surface recordings from the lingual muscles were carried out in six selected stroke patients who presented with a unilateral lingual paralysis after a limited monohemispheric ischemia. The first examination was performed during the symptomatic stage (t1) and was repeated after complete recovery of lingual function had been established (t2). The cortical motor output patterns were analyzed and compared with the data from 40 healthy controls. In the controls TMS of either hemisphere invariably produced contralateral and ipsilateral compound muscle action potentials (CMAPs), elicited through crossed and uncrossed central motor pathways, respectively. In most individuals an asymmetric cortical motor output pattern was found, as significantly greater mean CMAPs of shorter onset latencies were recorded from the contralateral lingual muscles than from the ipsitateral responses. In the six patients with a unilateral lingual paralysis a similar pattern was found on initial examination by stimulating the intact hemisphere, whereas TMS of the affected hemisphere failed to elicit any CMAP bilaterally. At t2 all patients had regained normal lingual function. Only one patient showed evidence of a complete recovery of the primarily affected hemisphere, as TMS now elicited normal CMAPs bilaterally. In the remaining five patients the unilateral interruption of the corticonuclear pathways persisted in spite of complete functional recovery. In these subjects the recovery of symmetric lingual movements must be attributed to the intact hemisphere. From this it is concluded that recovery of a unilateral lingual paralysis after restricted monohemispheric lesions is possible without recovery of the cortical motor projections from the affected hemisphere. In these cases the intact hemisphere is responsible for restoration of normal lingual movements, most likely by potentiating the effect of preexisting uncrossed motor pathways.
经颅磁刺激（TMS）运动皮层被用于研究人类大脑半球大面积卒中后运动重组的基本机制。我们试图阐明完整半球在舌肌运动恢复中的可能作用，并评估投射至这些中线肌肉的已存在的非交叉运动通路的代偿性利用情况。对6例经选择的卒中患者进行了TMS及舌肌双侧表面记录，这些患者在局限性单半球缺血后出现单侧舌瘫。首次检查在症状期（t1）进行，并在舌功能完全恢复后（t2）重复检查。分析皮层运动输出模式，并与40名健康对照者的数据进行比较。在对照者中，刺激任一半球的TMS均能分别通过交叉和非交叉的中枢运动通路引出对侧和同侧复合肌肉动作电位（CMAP）。在大多数个体中发现了不对称的皮层运动输出模式，因为从对侧舌肌记录到的平均CMAP的起始潜伏期明显短于同侧反应，且幅度明显更大。在6例单侧舌瘫患者中，首次检查时刺激完整半球发现了类似的模式，而刺激患侧半球未能双侧引出任何CMAP。在t2时，所有患者均恢复了正常舌功能。只有1例患者显示主要受累半球完全恢复，因为此时TMS能双侧引出正常CMAP。在其余5例患者中，尽管功能完全恢复，但皮质核束通路的单侧中断仍然存在。在这些受试者中，对称舌运动的恢复必定归因于完整半球。由此得出结论，局限性单半球病变后单侧舌瘫有可能在患侧半球的皮层运动投射未恢复的情况下恢复。在这些病例中，完整半球负责恢复正常舌运动，很可能是通过增强已存在的非交叉运动通路的作用来实现的。
